Project Summary Megadalton Solutions (Megadalton) is a startup company founded by Martin Jarrold and David Clemmer in August 2018 in Bloomington, Indiana. Megadalton aims to commercialize charge detection mass spectrometry (CDMS). This proposal describes a key step towards realizing this goal. We propose the construction of a standalone CDMS instrument that will greatly expand a nascent fee-for-measurement business dedicated to characterizing gene therapy products. Gene therapy provides the opportunity for a one-time cure to some of the most devastating diseases. The first FDA approval for a gene therapy treatment was in 2017. Currently there are more than 2,400 registered gene therapy clinical trials and so enormous growth is expected in the next few years. In gene therapy, the genome is usually inserted into cells by a virus vector. The active agent (the vector and its encapsulated genome) is large, 10-100 nm in diameter, and difficult to characterize. The number of functional particles in a preparation is often small and shows significant lot-to-lot variability. It is difficult to optimize a production process without good analytical tools to quickly characterize the product. Mass spectrometry (MS) is one of the most powerful analytical tools used to characterize conventional pharmaceuticals. However, commercial mass spectrometers have an upper mass limit of around a megadalton (1 MDa = 1,000,000 Da where 1 Da is the mass of a hydrogen atom). This mass limit is much too low for gene therapy products, where masses can be in the hundreds of megadaltons. CDMS is a single particle technique where the m/z (mass to charge) ratio and charge are measured directly for individual ions. This allows MS measurements to be extended beyond the current 1 MDa limit, and into the megadalton to gigadalton regime. Proof of concept studies for adeno-associated virus (AAV) based gene therapy products show that CDMS can characterize particle heterogeneity. In this case, empty particles, particles with the full genome, and particles with a partial genome, were easily resolved. Megadalton is establishing a fee-for-measurement business to support gene therapy product development. Contracts have been signed with a small number of pharmaceutical companies to perform CDMS measurements on AAV vectors. In order to meet immediate demand, Megadalton must expand measurement capacity. The proposed standalone instrument described in this proposal will allow this expansion. As part of this project, we will develop new assays for AAV based gene therapy products and assays will be developed for other vectors such as adenovirus. The standalone instrument will also serve as a prototype that will be used to develop research-grade instruments for sales to expert MS users with interests in CDMS. Sales of CDMS instruments is another key objective in our commercialization plan as it will allow other scientists to explore problems that can be addressed by mass measurements in the megadalton to gigadalton regime. New measurement tools, such as CDMS, open up new domains of research and lead to unexpected discoveries.